As schools seek to improve learning, many are moving towards sophisticated and high-stakes testing regimes. What isn't tested doesn't matter. To sharpen the focus on the competencies demanded by tests, schools are devoting an ever-greater share of resources to a few, basic subject areas, while reducing - even eliminating - time spent on subjects not tested. A casualty among these has been physical education. This brief summarizes the evidence against this trend. It presents concrete evidence that school-based sports and physical activity during the school day can improve learning and test scores. There is a positive association between mental and physical fitness. Although evidence is drawn from the United States, the conclusions can be adapted more universally. To date, there are no rigorous studies on the impact of sports and physical activity on learning in Latin America and the Caribbean.